Article of alumina and method of making same.



No Drawing.

' UNITED ST -rise PATENTOFFICE;

LEWI- ,s a uummna. or menu rants. amwz'o ,3 3 r comm, or woncnsrna, na umm; or ummu AND na'rnon oaks-nus? sens To all whom it may concern:

Be it known that I, Lnwts E. SAUNDERS, a citizen of the United States,residing at Niagara Falls, in the county of Niagara and State of NewYork, have invented certain -new and useful Improvements in Articles ofAlumina and Methods of Making Same, of which the following is aspecification.

This invention relates to the manufacture of highly refractory articlessuch as crucibles, tubes, bricks, or the like consisting essentially ofpreviously molten alumina in the form of grains or discrete particles,bonded by an aluminous deposit.

It is Well known that articles consisting of particles of alumina bondedby fireclay or like ceramic bond are less refractory under hightemperature conditions than the alumina itself, not only by reason'ofthe lower melting point of the bonding agent but because of the fiuxingaction of the bond.

upon the alumina.

According to my invention the aluminous particles are bonded by analuminous bonding agent, preferably derived from the particlesthemselves by partial or superficial solution of these particles in a.flux or temporary bond which is subsequently expelled by heat.

That the invention may be clearly understood it will be describedbyreference to certain specific embodiments, although it will beunderstood that the principle may be variously applied. For example Imay proceed substantially as follows: Alumina which has solidified'froma state of fusion is crushed and graded, and is then mixed with a smallproportion say four to eight per cent. of a bonding agent which in themolten state possesses a solvent action on bonded together.

Specification of Letters Extent. Sept, 10, Application filed December 21am. enn xaieaaos.

and subjected to a; very high temperature,

whereupon the following actions occur. The bonding agent fuses anddissolves aluagent is volatilized, with or without decomposition, and isexpelled, leaving an interstitial deposit of previously dissolvedalumina. Preferably ultimately raised to a point at which the particlesor grains ofalumina. begin to soften, whereby they are firmly fritted orAn electric furnace or kiln is preferred for the baking or for the finalstages thereof but may not be required in all cases. 1

In forming the articles the temperature is carried gradually beyond thepoint at which the tem orary binders are expelled, and to the po nt atwhich the aluminous particles or the interstitial alumina, diepositedfrom the flux, begins to soften, under which conditions the softenedalumina is capable of exerting a bonding effect upon the solidparticles. The time of heating necessary to accomplish this result willof course depend largely upon the size and shape of the articles.

Obviously the bonding agents employed may contain alumina, or mayconsist of solutionsof alumina in the fluxes named above, in which casethe interstitial deposit is derived inpart only from the particles to bethe temperature is bonded, or it may even be derived entirely from thebond.

The aluminous articles to be bonded may consist of pure alumina or theymay contain such impurities as are commonly present in commercialaluminous products. The

process presents special advantages however as applied to alumina ofsubstantial purity, as the material is then free from the fluxing actionof oxidized impurities as 'well as from the fluxing action of anordinary ceramic bond, and is extremely refractory under heat.

I claim: 1.

1. The-method of making molded articles consisting essentially ofalumina, which consists in bonding aluminous particles by a flux havinga solvent effect upon alumina,

and thereafter heating. the article to a temperature approximating themelting or a temperature approximating the melting or softening point ofpure alumina, whereby Softening point of pure alumina. l0 the flux isexpelled and the particles are In testimony whereofil afiix my signaturebonded by the softened alumina. in'presence of two witnesses.

2. A. molded article consisting essen- LEWIS E. SAUNDERS. tially ofgrains or particles of alumina hav- W'itnesses: ing an interstitial bondof previously dis- C. P. Towxsnxb, solved alumina, the mass frittedtogether at R. P. CAPRON.

